Eletropolimerização de aminofenóis para desenvolvimento de biossensores eletroquímicos aplicados à detecção de gene específico para câncer de próstata

Abstract

The prostate cancer in initial stages is completely asymptomatic. It is detected in routine exams by digital rectal exam. The diagnosis by PSA must be followed by a rectal ultrasonography being necessary the development of diagnostic platforms that may generate fast results with specificity, sensibility and low costs, features found on biological sensors. Among these biosensors, there are those based on DNA. Polymers as poly(aminophenols) are support matrices and can be used for the immobilization of biomolecules due to their features such as excellent permeability, selectivity, reproducibility and fast response. It was possible the electropolymerization of 2-aminophenol and 3-aminophenol. This polymer presents a self-limited growth and non-conducting behavior, confirmed in solution containing the redox pair Fe2+/Fe3+ while that polymer presents a polymeric film with conducting properties. These data are corroborated by EIS through analysis of resistance values, low for poly(2-aminophenol) and high for poly(3-aminophenol). Measurements of mass made by MECQ points a greater amount of polymeric film for poly(3-aminophenol) than for poly(2-aminophenol). Increasing the pH values results in a shift on the potential of the monomer oxidation to more cathodic potentials and a decreasing on the current values. SEMs and AFMs show rough films with different thickness, thinner to poly(3-aminophenol). FTIR results suggest possible polymerization through NH2 with the presence of free OH bands, due to the possibility of C-N-C bounds of secondary aromatic amines. The detection of purinic and pyrimidinic bases, isolated and in a mix, was possible showing that the interactions between them and the polymeric films occur by a similar mechanism. Experiments of immobilization of prostate cancer specific PCR products, with 277 base pairs were performed, denatured and hybridizated with ferrocenecarboxyaldheyde as mediator for the detection process. It is possible the construction of modified electrodes with polymeric films derived from 2-aminophenol and 3-aminophenol, presenting distinct spectroscopic and electrochemical properties. The polymers can be used as DNA nitrogenated bases detection matrices and they have the possibility of being used for biosensor construction.